Aromatic amine derivative, and organic electroluminescent element using same

ABSTRACT

An aromatic amine derivative represented by formula (1): 
     
       
         
         
             
             
         
       
     
     wherein R 1 , R 2 , R 3 , L, Ar 1 , Ar 2 , k, m, and n are the same as defined in the specification, is useful as a material for an organic EL device and realizes an organic EL device with a high efficiency and a long lifetime even when driving it at a low voltage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of prior U.S. applicationSer. No. 15/854,404, filed Dec. 26, 2017, the disclosure of which isincorporated herein by reference in its entirety. U.S. application Ser.No. 15/854,404 is a continuation application of prior U.S. applicationSer. No. 14/424,656, filed Feb. 27, 2015, the disclosure of which isincorporated herein by reference in its entirety. U.S. application Ser.No. 14/424,656 is the National Stage of PCT/JP13/073187, filed Aug. 29,2013, the disclosure of which is incorporated herein by reference in itsentirety. U.S. application Ser. No. 14/424,656 claims priority toJapanese Application No. 2012-191939, filed Aug. 31, 2012, thedisclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to aromatic amine derivatives and organicelectroluminescence devices using the aromatic amine derivatives. Forexample, the present invention relates to aromatic amine derivativeshaving a substituted or unsubstituted 9,9-diphenylfluorene skeleton andorganic electroluminescence devices employing the aromatic aminederivative.

BACKGROUND ART

Generally, an organic electroluminescence (EL) device includes an anode,a cathode, and at least one organic thin film layers which areinterposed between the anode and the cathode. When applying a voltagebetween both electrodes, electrons are injected into an emission regionfrom the cathode side and holes are injected into the emission regionfrom the anode side. The injected electrons and holes are recombined inthe emission region to generate an excited state. When the excited statereturns to a ground state, light is emitted. Therefore, to obtain ahigh-efficiency organic EL device, it is important to develop a compoundwhich efficiently transports electrons or holes into an emission regionand facilitates the recombination of electron and hole.

Generally, when driving or storing an organic EL device in ahigh-temperature environment, various problems occur, for example, theemission color is changed, the emission efficiency is reduced, thedriving voltage is increased, and the emission life is shortened. Toeliminate these drawbacks, various hole transporting materials have beenproposed, for example, Patent Document 1 discloses an aromatic aminederivative in which a N-carbazolyl group is directly bonded to a9,9-diphenylfluorene skeleton, Patent Document 2 discloses an aromaticamine derivative in which a 3-carbazolyl group is directly bonded to a9,9-dimethylfluorene skeleton, Patent Document 3 discloses an aromaticamine derivative in which a N-carbazolylphenyl group is bonded to a9,9-diphenylfluorene skeleton via a nitrogen atom, and Patent Document 4discloses an aromatic amine derivative in which a 3-carbazolyl group isbonded to a 9,9-diphenylfluorene skeleton via a nitrogen atom.

However, the aromatic amine derivatives disclosed in Patent Documents 1to 4 are still insufficient for reducing the driving voltage andprolonging the lifetime. Therefore, a further improvement has beenrequired.

Patent Document 5 proposes an aromatic amine derivative which includes askeleton selected from a fluorene skeleton, a carbazole skeleton, adibenzofuran skeleton, and a dibenzothiophene skeleton and teaches thatan organic EL device in which the aromatic amine derivative is used as amaterial for an organic EL device, particularly as a hole transportingmaterial, is capable of driving a low voltage and has a long lifetime.Patent Document 5 discloses a compound in which a diarylamino group isbonded to 2-position of a 9,9-diphenylfluorene skeleton. In the proposedcompound, a carbazole skeleton, a dibenzofuran skeleton, or adibenzothiophene skeleton must be bonded to a terminal end of one arylgroup of the diarylamino group. In all the exemplary compounds having a9,9-diphenylfluorene skeleton which are disclosed in Patent Document 5,a biphenylene group intervenes between the terminal groups and thenitrogen atom. However, a 2-diarylamino-9,9-diphenyl fluorene compoundhaving such an intervening biphenylene group is insufficient in theemission efficiency when driving at a low voltage and also insufficientin the lifetime (see Examples 1-1 to 1-4 and Comparative Examples 1-1 to1-2 described herein). Therefore, it has been required to develop amaterial for an organic EL device, particularly a hole transportingmaterial, which can be synthesized easily and realize an organic ELdevice having a high efficiency when driving at a low voltage andlong-lifetime.

CITATION LIST Patent Documents

-   Patent Document 1: WO 07/148660-   Patent Document 2: WO 08/062636-   Patent Document 3: US 2007/0215889-   Patent Document 4: JP 2005-290000A-   Patent Document 5: WO 2011/021520

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention has been made in view of solving the aboveproblems and an object of the invention is to provide a long-lifetime,high-efficiency organic EL device which is capable of driving at a lowvoltage and provide a material for an organic EL device, for example, ahole transporting material, which realizes such an organic EL device.

Means for Solving the Problems

As a result of extensive research, the inventors have found that acompound wherein a disubstituted amino group is bonded to 2-position ofa 9,9-diphenylfluorene skeleton directly or indirectly and at least onesubstituent of the disubstituted amino group is bonded to the nitrogenatom directly or via a phenylene group is excellent in the holeinjecting ability and the hole transporting ability, and further foundthat such a compound realizes a long-lifetime, high-efficiency organicEL device which is capable of driving at a low voltage.

The present invention provides an aromatic amine derivative representedby formula (1):

in formula (1), Ar¹ represents a group selected from formulae (2) to(4):

Ar² represents a group selected from formulae (6) to (15):

in formulae (1) to (4) and (10) to (14), L represents a single bond or adivalent group represented by formula (16), and when the aromatic aminederivative represented by formula (1) includes groups L, the groups Lmay be the same or different; [14]

in formulae (1) to (4) and (6) to (16), R′ represents a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 50 ring carbonatoms, a halogen atom, a substituted or unsubstituted fluoroalkyl grouphaving 1 to 20 carbon atoms, a substituted or unsubstituted alkoxy grouphaving 1 to 20 carbon atoms, a substituted or unsubstituted fluoroalkoxygroup having 1 to 20 carbon atoms, or a cyano group, and when groups R′exist, the groups R′ may be the same or different;

in formula (1), R² and R³ may be the same or different and independentlyrepresent a hydrogen atom, a substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms, a substituted or unsubstituted aryl grouphaving 6 to 50 ring carbon atoms, a substituted or unsubstitutedheterocyclic group having 3 to 50 ring atoms, a halogen atom, asubstituted or unsubstituted fluoroalkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted alkoxy group having 1 to 20 carbonatoms, a substituted or unsubstituted fluoroalkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to50 ring carbon atoms, or a cyano group, when groups R² exist, the groupsR² may be the same or different, and when groups R³ exist, the groups R³may be the same or different; [17] in formulae (4) and (14), two groupsR⁴ may be the same or different and independently represent a hydrogenatom, a substituted or unsubstituted alkyl group having 1 to 20 carbonatoms, a substituted or unsubstituted aryl group having 6 to 50 ringcarbon atoms, a substituted or unsubstituted heterocyclic group having 3to 50 ring atoms, a halogen atom, a substituted or unsubstitutedfluoroalkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted alkoxy group having 1 to 20 carbon atoms, a substituted orunsubstituted fluoroalkoxy group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryloxy group having 6 to 50 ring carbonatoms, or a cyano group, and when the aromatic amine derivativerepresented by formula (1) includes a group represented by formula (4)and/or a group represented by formula (14), R², R³ and R⁴ may be thesame or different;

-   -   k represents an integer of 1 to 5;    -   m represents an integer of 1 to 4; and    -   n represents an integer of 1 to 3.

The present invention further provides an organic electroluminescencedevice comprising an anode, a cathode, and at least one organic thinfilm layers between the anode and the cathode, wherein the at least oneorganic thin film layers comprises a light emitting layer and at leastone of the organic thin film layers comprises the aromatic aminederivative represented by formula (1).

Effects of the Invention

By using the aromatic amine derivative of the invention, along-lifetime, high-efficiency organic EL device capable of driving at alow voltage is obtained.

MODE FOR CARRYING OUT THE INVENTION

The term of “a to b carbon atoms” referred to by “a substituted orunsubstituted X group having a to b carbon atoms” used herein is thenumber of carbon atoms of the unsubstituted X group and does not includeany carbon atom in the substituent of the substituted X group.

The definition of “hydrogen atom” used herein includes isotopesdifferent in the neutron numbers, i.e., light hydrogen (protium), heavyhydrogen (deuterium), and tritium.

The optional substituent referred to by “substituted or unsubstituted”used herein is selected from the group consisting of an alkyl grouphaving 1 to 50, preferably 1 to 10, more preferably 1 to 5 carbon atoms;a cycloalkyl group having 3 to 50, preferably 3 to 6, more preferably 5or 6 ring carbon atoms; an aryl group having 6 to 50, preferably 6 to24, more preferably 6 to 12 ring carbon atoms; an aralkyl group having 1to 50, preferably 1 to 10, more preferably 1 to 5 carbon atoms whichincludes an aryl group having 6 to 50, preferably 6 to 24, morepreferably 6 to 12 ring carbon atoms; an amino group; a mono- ordialkylamino group having an alkyl group having 1 to 50, preferably 1 to10, more preferably 1 to 5 carbon atoms; a mono- or diarylamino grouphaving an aryl group having 6 to 50, preferably 6 to 24, more preferably6 to 12 ring carbon atoms; an alkoxy group having an alkyl group having1 to 50, preferably 1 to 10, more preferably 1 to 5 carbon atoms; anaryloxy group having an aryl group having 6 to 50, preferably 6 to 24,more preferably 6 to 12 ring carbon atoms; a mono-, di- ortri-substituted silyl group having a substituent selected from an alkylgroup having 1 to 50, preferably 1 to 10, more preferably 1 to 5 carbonatoms and an aryl group having 6 to 50, preferably 6 to 24, morepreferably 6 to 12 ring carbon atoms; a heteroaryl group having 5 to 50,preferably 5 to 24, more preferably 5 to 12 ring atoms and having 1 to5, preferably 1 to 3, more preferably 1 to 2 hetero atoms, such as anitrogen atom, an oxygen atom and a sulfur atom; a halogen atom selectedfrom a fluorine atom, a chlorine atom, a bromine atom and an iodineatom; a cyano group; and a nitro group.

The aromatic amine derivative of the invention is represented by formula(1):

In formula (1), Ar¹ represents a group selected from formulae (2) to(4):

In formula (1), Ar² represents a group selected from formulae (6) to(15):

In formulae (1) to (4) and (10) to (14), L represents a single bond or adivalent group represented by formula (16):

L in formula (1) represents preferably a single bond or a phenylenegroup and more preferably a single bond. L in formulae (2) to (4) and(10) to (14) represents preferably a single bond or a phenylene groupand more preferably a phenylene group and preferably bonds to 2- or4-position of a dibenzofuran skeleton and a dibenzothiophene skeletonand bonds to 2-position of a fluorene skeleton. When the aromatic aminederivative represented by formula (1) includes groups L, the groups Lmay be the same or different.

In formulae (1) to (4) and (6) to (16), R¹ represents a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 20, preferably 1 to5, and more preferably 1 to 4 carbon atoms, a substituted orunsubstituted aryl group having 6 to 50, preferably 6 to 24, and morepreferably 6 to 12 ring carbon atoms, a halogen atom, a substituted orunsubstituted fluoroalkyl group having 1 to 20, preferably 1 to 5, andmore preferably 1 to 4 carbon atoms, a substituted or unsubstitutedalkoxy group having 1 to 20, preferably 1 to 5, and more preferably 1 to4 carbon atoms, a substituted or unsubstituted fluoroalkoxy group having1 to 20, preferably 1 to 5, and more preferably 1 to 4 carbon atoms, ora cyano group. When the aromatic amine derivative represented by formula(1) includes groups R′, the groups R′ may be the same or different.

Examples of the alkyl group having 1 to 20 carbon atoms include a methylgroup, an ethyl group, a n-propyl group, an isopropyl group, a n-butylgroup, an isobutyl group, a s-butyl group, a t-butyl group, a pentylgroup (inclusive of isomeric groups), a hexyl group (inclusive ofisomeric groups), a heptyl group (inclusive of isomeric groups), anoctyl group (inclusive of isomeric groups), a nonyl group (inclusive ofisomeric groups), a decyl group (inclusive of isomeric groups), anundecyl group (inclusive of isomeric groups), and a dodecyl group(inclusive of isomeric groups), with a methyl group, an ethyl group, an-propyl group, an isopropyl group, a n-butyl group, an isobutyl group,a s-butyl group, a t-butyl group, and a pentyl group (inclusive ofisomeric groups) being preferred, a methyl group, an ethyl group, an-propyl group, an isopropyl group, a n-butyl group, an isobutyl group,a s-butyl group, and a t-butyl group being more preferred, and a methylgroup and a t-butyl group being particularly preferred.

Examples of the aryl group having 6 to 50 ring carbon atoms include aphenyl group, a naphthylphenyl group, a biphenylyl group, a terphenylylgroup, a biphenylenyl group, a naphthyl group, a phenylnaphthyl group,an acenaphthylenyl, an anthryl group, a benzanthryl group, an aceanthrylgroup, a phenanthryl group, a benzophenanthryl group, a phenalenylgroup, a fluorenyl group, a 9,9-dimethylfluorenyl group, a7-phenyl-9,9-dimethylfluorenyl group, a pentacenyl group, a picenylgroup, a pentaphenyl group, a pyrenyl group, a chrysenyl group, abenzochrysenyl group, a s-indacenyl group, an as-indacenyl group, afluoranthenyl group, and a perylenyl group, with a phenyl group, anaphthylphenyl group, a biphenylyl group, a terphenylyl group, anaphthyl group, and a 9,9-dimethylfluorenyl group being preferred, aphenyl group, a biphenylyl group, a naphthyl group, and a9,9-dimethylfluorenyl group being more preferred, and a phenyl groupbeing particularly preferred.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom, with a fluorine atom being particularlypreferred.

Examples of the fluoroalkyl group having 1 to 20 carbon atoms include agroup obtained by substituting a fluorine atom for at least one hydrogenatom, preferably 1 to 7 hydrogen atom of the alkyl group having 1 to 20carbon atoms mentioned above, and preferably a heptafluoropropyl group,a pentafluoroethyl group, a 2,2,2-trifluoroethyl group, and atrifluoromethyl group, more preferably a pentafluoroethyl group, a2,2,2-trifluoroethyl group, and a trifluoromethyl group, andparticularly preferably a trifluoromethyl group.

Examples of the alkoxy group having 1 to 20 carbon atoms are representedby —OR¹⁰, wherein R¹⁰ represents the alkyl group having 1 to 20 carbonatoms mentioned above, and preferably a t-butoxy group, a propoxy group,an ethoxy group or a methoxy group, more preferably an ethoxy group or amethoxy group, and particularly preferably a methoxy group.

Examples of the fluoroalkoxy group having 1 to 20 carbon atoms arerepresented by —OR¹¹, wherein R¹¹ represents the fluoroalkyl grouphaving 1 to 20 carbon atoms mentioned above, and preferably aheptafluoropropoxy group, a pentafluoroethoxy group, a2,2,2-trifluoroethoxy group, or a trifluoromethoxy group, morepreferably a pentafluoroethoxy group, a 2,2,2-trifluoroethoxy group, ora trifluoromethoxy group, and particularly preferably a trifluoromethoxygroup.

In a preferred embodiment of the invention, R′ to be bonded to thefluorene skeleton of formula (1) is preferably a hydrogen atom, thehalogen atom mentioned above (a fluorine atom), the alkyl groupmentioned above (a methyl group and a t-butyl group), and the aryl groupmentioned above (a phenyl group). R¹ is preferably bonded to 7-positionof the fluorene skeleton and particularly preferably a hydrogen atom.

In a preferred embodiment of the invention, R¹ of formulae (2), (3),(12) and (13) is preferably a hydrogen atom, the alkyl group mentionedabove (a methyl group), or the aryl group mentioned above (a phenylgroup), which is preferably bonded to 6- or 8-position of thedibenzofuran skeleton and the dibenzothiophene skeleton. R¹ isparticularly preferably a hydrogen atom.

In a preferred embodiment of the invention, R¹ of formulae (4), (14) and(15) is preferably a hydrogen atom, a methyl group, a t-butyl group, ora phenyl group, which is preferably bonded to 7-position of the fluoreneskeleton or 3- or 6-position of the carbazole skeleton. R¹ isparticularly preferably a hydrogen atom.

In a preferred embodiment of the invention, R¹ of formulae (6) to (9) ispreferably selected from a hydrogen atom, the alkyl group mentionedabove (a methyl group and a t-butyl group), the halogen atom mentionedabove (a fluorine atom), the fluoroalkyl group mentioned above (atrifluoromethyl group), the alkoxy group mentioned above (a methoxygroup), the fluoroalkoxy group mentioned above (a trifluoromethoxygroup), and a cyano group. R¹ is preferably bonded to o-position and/orp-position of the terminal phenyl group and o-position and/or m-positionof the phenylene group. R¹ is particularly preferably a hydrogen atom.

In a preferred embodiment of the invention, W of formulae (10) and (11)is preferably a hydrogen atom, a methyl group, a t-butyl group, or aphenyl group. IV is preferably bonded to 6- or 7-position of thenaphthalene skeleton. R¹ is particularly preferably a hydrogen atom.

In formula (1), R² and R³ may be the same or different and independentlyrepresent a hydrogen atom, a substituted or unsubstituted alkyl grouphaving 1 to 20, preferably 1 to 5, and more preferably 1 to 4 carbonatoms, a substituted or unsubstituted aryl group having 6 to 50,preferably 6 to 24, and more preferably 6 to 12 ring carbon atoms, asubstituted or unsubstituted heterocyclic group having 3 to 50,preferably 3 to 24, and more preferably 3 to 12 ring atoms, a halogenatom, a substituted or unsubstituted fluoroalkyl group having 1 to 20,preferably 1 to 5, and more preferably 1 to 4 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 20, preferably 1to 5, and more preferably 1 to 4 carbon atoms, a substituted orunsubstituted fluoroalkoxy group having 1 to 20, preferably 1 to 5, andmore preferably 1 to 4 carbon atoms, a substituted or unsubstitutedaryloxy group having 6 to 50, preferably 6 to 24, and more preferably 6to 12 carbon atoms, or a cyano group. When the aromatic amine derivativerepresented by formula (1) includes groups R², the groups R² may be thesame or different, and when includes groups R³, the groups R³ may be thesame or different.

The details of the alkyl group having 1 to 20 carbon atoms, the arylgroup having 6 to 50 ring carbon atoms, the halogen atom, thefluoroalkyl group having 1 to 20 carbon atoms, the alkoxy group having 1to 20 carbon atoms, and the fluoroalkoxy group having 1 to 20 carbonatoms for R² and R³ are the same as defined above with respect to R¹.

The heterocyclic group having 3 to 50 ring atoms includes at least one,preferably 1 to 3 hetero atoms, for example, a nitrogen atom, a sulfuratom, and an oxygen atom. Examples thereof include a pyrrolyl group, afuryl group, a thienyl group, a pyridyl group, a pyridazinyl group, apyrimidinyl group, a pyrazinyl group, a triazinyl group, an imidazolylgroup, an oxazolyl group, a thiazolyl group, a pyrazolyl group, anisoxazolyl group, an isothiazolyl group, an oxadiazolyl group, athiadiazolyl group, a triazolyl group, an indolyl group, an isoindolylgroup, a benzofuranyl group, an isobenzofuranyl group, a benzothiophenylgroup, an indolizinyl group, a quinolizinyl group, a quinolyl group, anisoquinolyl group, a cinnolyl group, a phthalazinyl group, aquinazolinyl group, a quinoxalinyl group, a benzimidazolyl group, abenzoxazolyl group, a benzothiazolyl group, an indazolyl group, abenzisoxazolyl group, a benzisothiazolyl group, a dibenzofuranyl group,a dibenzothiophenyl group, a phenanthridinyl group, an acridinyl group,a phenanthrolinyl group, a phenazinyl group, a phenothiazinyl group, aphenoxazinyl group, and a xanthenyl group. Preferred are a furyl group,a thienyl group, a pyridyl group, a pyridazinyl group, a pyrimidinylgroup, a pyrazinyl group, a triazinyl group, a benzofuranyl group, abenzothiophenyl group, a dibenzofuranyl group, and a dibenzothiophenylgroup. More preferred are a benzofuranyl group, a benzothiophenyl group,a dibenzofuranyl group, and a dibenzothiophenyl group.

The aryloxy group having 6 to 50 ring carbon atoms is represented by—OR¹², wherein R¹² represents the aryl group having 6 to 50 ring carbonatoms which is defined above with respect to R¹, preferably a terphenylgroup, a biphenyl group or a phenyl group, more preferably a biphenylgroup or a phenyl group, and particularly preferably a phenyl group.

In a preferred embodiment of the invention, each of R² and R³ preferablyrepresents a hydrogen atom, the alkyl group mentioned above (a methylgroup or a t-butyl group), the aryl group mentioned above (a phenylgroup), or a cyano group. Each of R² and R³ is preferably bonded top-position of each phenyl group. Each of R² and W is particularlypreferably a hydrogen atom.

In formulae (4) and (14), two groups R⁴ may be the same or different andindependently represent a hydrogen atom, a substituted or unsubstitutedalkyl group having 1 to 20, preferably 1 to 5, and more preferably 1 to4 carbon atoms, a substituted or unsubstituted aryl group having 6 to50, preferably 6 to 24, and more preferably 6 to 12 carbon atoms, asubstituted or unsubstituted heterocyclic group having 3 to 50,preferably 3 to 24, and more preferably 3 to 12 ring atoms, a halogenatom, a substituted or unsubstituted fluoroalkyl group having 1 to 20,preferably 1 to 5, and more preferably 1 to 4 carbon atoms, asubstituted or unsubstituted alkoxy group having 1 to 20, preferably 1to 5, and more preferably 1 to 4 carbon atoms, a substituted orunsubstituted fluoroalkoxy group having 1 to 20, preferably 1 to 5, andmore preferably 1 to 4 carbon atoms, a substituted or unsubstitutedaryloxy group having 6 to 50, preferably 6 to 24, and more preferably 6to 12 carbon atoms, or a cyano group. When the aromatic amine derivativerepresented by formula (1) includes the group represented by formula (4)and/or the group represented by formula (14), R², R³ and R⁴ may be thesame or different.

The groups for two groups R⁴ are the same as defined above with respectto R² and R³. In a preferred embodiment of the invention, each of twogroups R⁴ is particularly preferably selected from the alkyl groupmentioned above (a methyl group) and the aryl group mentioned above (aphenyl group).

The subscript k represents an integer of 1 to 5, preferably 1 to 3, andmore preferably 1.

The subscript m represents an integer of 1 to 4, preferably 1 to 3, andmore preferably 1.

The subscript n represents an integer of 1 to 3, preferably 1 to 2, andmore preferably 1.

The aromatic amine derivative represented by formula (1) is preferablyrepresented by formula (20):

wherein Ar¹, Ar², R¹ to R³, k, m, and n are the same as defined informula (1).

When the fluorene skeleton is directly bonded to the nitrogen atom asshown in formula (20), the ionization potential of the aromatic aminederivative is lowered. Therefore, the energy barrier of a light emittinglayer to an anode or a hole injecting layer is reduced to facilitate theelectron injection to the light emitting layer, thereby reducing thedriving voltage of an organic EL device.

Ar¹ is preferably a group selected from formulae (21) to (25):

wherein L, R¹, R⁴, and m are the same as defined in formulae (2) to (4).

Ar¹ is more preferably a group selected from formulae (26) to (30).

wherein R¹, R⁴, and m are the same as defined in formulae (2) to (4).

In formulae (21) to (30), when L or the phenylene group is bonded to thedibenzofuran skeleton or the dibenzothiophene skeleton at o-positionwith respect to the oxygen atom or the sulfur atom, the lifetime isexpected to be improved, while the efficiency is expected to be improvedwhen bonded at p-position with respect to the oxygen atom or the sulfuratom. When L or the phenylene group is bonded to 2-position of thefluorene skeleton, the driving voltage is expected to be reduced.

The group represented by any of formulae (26) to (30) partly includes ap-biphenyl structure. The p-position of the benzene ring directly bondedto the central nitrogen atom is a portion with a high electron densityand an electrochemically weak portion. In contrast, by the p-biphenylstructure, i.e., by protecting the p-position of the benzene ring with aphenyl group, the stability of the compound is improved and thedeterioration of the material is prevented, and therefore, the lifetimeof an organic EL device is prolonged.

Each of formulae (7), (8) and (9) for Are is preferably represented byany of formulae (7-1), (7-2), (8-1), and (9-1):

wherein R¹, k, m, and n are the same as defined in formulae (7), (8) and(9).

Each of formulae (12), (13) and (14) for Are is preferably representedby any of formulae (31) to (35):

in formulae (31) to (35), R¹, R⁴, L, and m are the same as defined informulae (12) to (14), and more preferably represented by any offormulae (36) to (40):

in formulae (31) to (35), R¹, R⁴ and m are the same as defined informulae (2) to (4).

Examples of the aromatic amine derivative represented by formula (1) areshown below, although not limited to the following compounds.

The aromatic amine derivative represented by formula (1) is useful as amaterial for an organic EL device, in particular, as a hole injectinglayer material or a hole transporting layer material. The productionmethod of the aromatic amine derivative of the invention is notparticularly limited and one of ordinary skill in the art could easilyproduce it by utilizing or modifying known synthesis reactions whilereferring to the examples described below.

The structure of the organic EL device of the invention will bedescribed below.

Examples of the typical device structure of the organic EL device of theinvention include the following (1) to (13), although not particularlylimited thereto. The device structure (8) is preferably used.

(1) anode/light emitting layer/cathode;(2) anode/hole injecting layer/light emitting layer/cathode;(3) anode/light emitting layer/electron injecting layer/cathode;(4) anode/hole injecting layer/light emitting layer/electron injectinglayer/cathode;(5) anode/organic semiconductor layer/light emitting layer/cathode;(6) anode/organic semiconductor layer/electron blocking layer/lightemitting layer/cathode;(7) anode/organic semiconductor layer/light emitting layer/adhesionimproving layer/cathode;(8) anode/hole injecting layer/hole transporting layer/light emittinglayer/(electron transporting layer/) electron injecting layer/cathode;(9) anode/insulating layer/light emitting layer/insulatinglayer/cathode;(10) anode/inorganic semiconductor layer/insulating layer/light emittinglayer/insulating layer/cathode;(11) anode/organic semiconductor layer/insulating layer/light emittinglayer/insulating layer/cathode;(12) anode/insulating layer/hole injecting layer/hole transportinglayer/light emitting layer/insulating layer/cathode; and(13) anode/insulating layer/hole injecting layer/hole transportinglayer/light emitting layer/(electron transporting layer/)electroninjecting layer/cathode.

Since the aromatic amine derivative of the invention hardlycrystallizes, it can be used in any of the above organic thin filmlayers. In view of driving at a lower voltage, the aromatic aminederivative is preferably used in a hole injecting layer or a holetransporting layer and more preferably in a hole transporting layer. Theorganic EL device employing the aromatic amine derivative of theinvention is not only capable of driving at a low voltage but also has ahigh emission efficiency and a long lifetime.

The content of the aromatic amine derivative in an organic thin filmlayer, preferably in a hole injecting layer or a hole transporting layeris preferably 30 to 100 mol %, more preferably 50 to 100 mol %, stillmore preferably 80 to 100 mol %, and particularly preferablysubstantially 100 mol %, each based on the total components of theorganic thin film layers.

Each layer of a preferred embodiment of an organic EL device wherein thearomatic amine derivative of the invention is used in a holetransporting layer is described below.

Substrate

The organic EL device is generally prepared on a light-transmissivesubstrate. The light-transmissive substrate is a substrate forsupporting the organic EL device, which preferably has a lighttransmittance of 50% or higher to 400 to 700 nm visible lights and ispreferably flat and smooth.

Examples of the light-transmissive substrate include glass plates andsynthetic resin plates. Examples of the glass plate include plates ofsoda-lime glass, glass containing barium and strontium, lead glass,aluminosilicate glass, borosilicate glass, barium borosilicate glass,and quartz. Examples of the synthetic resin plate include plates of apolycarbonate resin, an acrylic resin, a polyethylene terephthalateresin, a polyether sulfide resin, and a polysulfone resin.

Anode

The anode has a function of injecting holes to a hole transporting layeror a light emitting layer and a material having a work function of 4 eVor more, preferably 4.5 eV or more is effective. Examples of thematerial for the anode include carbon, aluminum, vanadium, iron, cobalt,nickel, tungsten, silver, gold, platinum, palladium, alloys thereof,metal oxides, such as tin oxide and indium oxide, which are used as ITOsubstrate and NESA substrate, and organic conductive resins, such aspolythiophene and polypyrrole.

The anode may be obtained by forming the above anode material into athin film, for example, by a vapor deposition process or a sputteringprocess.

When the light emitted from the light emitting layer is taken throughthe anode, the transmittance of the anode to the emitted light ispreferably higher than 10%. The sheet resistance of the anode ispreferably several hundred Ω/□ or smaller. The thickness of the anode isgenerally 10 nm to 1 μm and preferably 10 to 200 nm, although variesdepending upon the used material.

Cathode

The cathode is formed by an electrode material, such as a metal, analloy, an electroconductive compound, or a mixture thereof, each havinga small work function (less than 4 eV). Examples thereof includemagnesium, calcium, tin, lead, titanium, yttrium, lithium, ruthenium,manganese, aluminum, lithium fluoride, and alloys thereof, although notparticularly limited thereto. Examples of the alloy includemagnesium/silver, magnesium/indium, lithium/aluminum, although notparticularly limited thereto. The ratio of the alloying metals issuitably selected according to the temperature of evaporation source,atmosphere, and vacuum level. The anode and cathode may be made into twoor more layered structure, if needed.

The cathode may be obtained by forming the above electrode material intoa thin film, for example, by a vapor deposition process or a sputteringprocess.

When the light emitted from the light emitting layer is taken throughthe cathode, the transmittance of the cathode to the emitted light ispreferably higher than 10%. The sheet resistance of the cathode ispreferably several hundred Ω/□ or smaller. The thickness of the cathodeis generally 10 nm to 1 μm and preferably 50 to 200 nm.

Insulating Layer

Since an electric field is applied to ultra-thin films, pixel defectsdue to leak and short circuit tend to easily occur. To prevent thedefects, a layer made of an insulating thin film layer may be disposedbetween the pair of electrodes.

Examples of the material for the insulating layer include aluminumoxide, lithium fluoride, lithium oxide, cesium fluoride, cesium oxide,magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride,aluminum nitride, titanium oxide, silicon oxide, germanium oxide,silicon nitride, boron nitride, molybdenum oxide, ruthenium oxide, andvanadium oxide. Mixtures and laminates of these compounds may be alsoused.

Light Emitting Layer

The light emitting layer has the following functions (1) to (3):

-   -   (1) injecting function: function of allowing holes from the        anode or the hole injecting layer to be injected to the light        emitting layer and allowing electrons from the cathode or the        electron injecting layer to be injected to the light emitting        layer, when an electric field is applied;    -   (2) transporting function: function of transporting injected        charges (electrons and holes) by the force of the electric        field; and    -   (3) light emitting function: function of providing the field for        recombination of electrons and holes to allow the emission of        light.

The light emitting layer may be different in the hole injection abilityand the electron injection ability, and also in the hole transportingability and the electron transporting ability each being expressed by ahole mobility or an electron mobility, respectively. Preferably, thelight emitting layer transports one kind of charges.

The host material and the doping material for use in the light emittinglayer are not particularly limited. Examples thereof include a fusedpolycyclic aromatic compound and its derivative, such as naphthalene,phenanthrene, rubrene, anthracene, tetracene, pyrene, perylene,chrysene, decacyclene, coronene, tetraphenylcyclopentadiene,pentaphenylcyclopentadiene, fluorene, spirofluorene,9,10-diphenylanthracene, 9,10-bis(phenylethinyl)anthracene, and1,4-bis(9′-ethinylanthracene)benzene; an organic metal complex such astris(8-quinolinolato)aluminum orbis(2-methyl-8-quinolinolato)-4-(phenylphenolinato)aluminum; anarylamine derivative; a styrylamine derivative; a stilbene derivative; acoumarin derivative; a pyran derivative; an oxazone derivative; abenzothiazole derivative; a benzoxazole derivative; a benzimidazolederivative; a pyrazine derivative; a cinnamic ester derivative; adiketopyrrolopyrrole derivative; an acridone derivative; and aquinacridone derivative. Preferred are an arylamine derivative and astyrylamine derivative, with a styrylamine derivative being morepreferred.

Hole Injecting Layer/Hole Transporting Layer

The hole injecting layer/hole transporting layer facilitates theinjection of holes into a light emitting layer, transports holes into anemission region, and has a large hole mobility and an ionization energygenerally as small as 5.7 eV or less. A material which transports holesto a light emitting layer at a smaller magnitude of electric field ispreferably used for the hole injecting layer/hole transporting layer.The hole mobility of the material is preferably 10⁻⁴ cm²/V·s or morewhen applying an electric field of 10⁴ to 10⁶ V/cm.

As described above, the aromatic amine derivative of the invention ispreferably used as a hole injecting layer material, particularly as ahole transporting layer material. The hole transporting layer may beformed from the aromatic amine derivative of the invention alone or incombination with another material which is not particularly limited aslong as it has preferred properties mentioned above and can be selectedfrom materials generally used as a hole transporting material in aphotoconductive material and known hole transporting materials used inorganic EL devices. In the present invention, a material which has ahole transporting ability and can be used in a hole transporting regionis called a hole transporting material.

Examples of the material for a hole transporting layer other than thearomatic amine derivative of the invention include a phthalocyaninederivative, a naphthalocyanine derivative, a porphyrin derivative,oxazole, oxadiazole, triazole, imidazole, imidazolone, imidazolethione,pyrazoline, pyrazolone, tetrahydroimidazole, oxazole, oxadiazole,hydrazone, acylhydrazone, polyarylalkane, stilbene, butadiene, benzidinetype triphenylamine, styrylamine type triphenylamine, diamine typetriphenylamine, derivatives thereof, and a polymeric material, such aspolyvinyl carbazole, polysilane, and a conductive polymer, although notparticularly limited thereto.

The material for a hole injecting layer is not particularly limited aslong as it has preferred properties mentioned above and can be selectedfrom materials generally used as a hole injecting material in aphotoconductive material and known hole transporting materials used inorganic EL devices. In the present invention, a material which has ahole injecting ability and can be used in a hole injecting region iscalled a hole injecting material. To enhance the electron injectingability, an electron-accepting compound may be added to the electroninjecting material.

In the organic EL device of the invention, a hexaazatriphenylenecompound represented by formula (A) is preferably used as the holeinjecting material.

In formula (A), R¹¹¹ to R¹¹⁶ independently represent a cyano group,—CONH₂, a carboxyl group, or —COOR¹¹⁷ (wherein R¹¹⁷ represents an alkylgroup having 1 to 20 carbon atoms), or R¹¹¹ and R¹¹², R¹¹³ and R¹¹⁴, orR¹¹⁵ and R¹¹⁶ may be boded to each other to represent —CO—O—CO—.

In a preferred embodiment, R¹¹¹ to R¹¹⁶ are the same and represent acyano group, —CONH₂, a carboxyl group, or —COOR¹¹⁷. In another preferredembodiment, R¹¹¹ and R¹¹², R¹¹³ and R¹¹⁴, and R¹¹⁵ and R¹¹⁶ are allbonded to each other to represent —CO—O—CO—.

Further examples of the hole transporting material usable in the organicEL device of the invention include an aromatic tertiary amine derivativeand a phthalocyanine derivative.

Examples of the aromatic tertiary amine derivative includetriphenylamine, tritolylamine, tolyldiphenylamine,N,N′-diphenyl-N,N′-(3-methylphenyl)-1,1′-biphenylyl-4,4′-diamine,N,N,N′,N′-(4-methylphenyl)-1,1′-phenyl-4,4′-diamine,N,N,N′,N′-(4-methylphenyl)-1,1′-biphenylyl-4,4′-diamine,N,N′-diphenyl-N,N′-dinaphthyl-1,1′-biphenylyl-4,4′-diamine,N,N′-(methylphenyl)-N,N′-(4-n-butylphenyl)-phenanthrene-9,10-diamine,N,N-bis(4-di-4-tolylaminophenyl)-4-phenyl-cyclohexane, and an oligomeror a polymer constituted by a unit derived from the above aromatictertiary amines, although not particularly limited thereto.

Examples of the phthalocyanine (Pc) derivative include, but not limitedto, a phthalocyanine derivative, such as H₂Pc, CuPc, CoPc, NiPc, ZnPc,PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl₂SiPc, (HO)AlPc,(HO)GaPc, VOPc, TiOPc, MoOPc, and GaPc-O-GaPc, and a naphthalocyaninederivative.

In addition, the organic EL device of the invention preferably comprisesa layer containing the aromatic tertiary amine derivative and/or thephthalocyanine derivative, for example, the hole transporting layer orthe hole injecting layer, between a light emitting layer and an anode.

To enhance the electron injecting ability, an electron-acceptingcompound may be added to the electron injecting material.

Electron Injecting Layer/Electron Transporting Layer

The electron injecting layer/electron transporting layer facilitates theinjection of electrons into a light emitting layer, transports electronsto an emission region, and has a large electron mobility. An adhesionimproving layer is an electron injecting layer which includes a materialhaving a particularly high adhesion to a cathode.

The emitted light is reflected by an electrode (cathode in this case).It has been known that the emitted light directly passing through ananode and the emitted light passing through the anode after reflected bythe electrode interfere with each other. To effectively utilize thisinterference effect, the thickness of the electron transporting layer isappropriately selected from several nanometers to several micrometers.When the thickness is large, the electron mobility is preferablyregulated to 10⁻⁵ cm²/Vs or more at an electric field of 10⁴ to 10⁶ V/cmin order to avoid the increase in voltage.

Examples of the material for use in the electron injecting layerinclude, but not limited to, fluorenone, anthraquinodimethane,diphenoquinone, thiopyraneclioxide, oxazole, oxadiazole, triazole,imidazole, perylenetetracarboxylic acid, fluorenylidenemethane,anthraquinodimethane, anthrone, and derivatives thereof. To enhance theelectron injecting ability, an electron-donating compound may be addedto the electron injecting material.

Examples of other effective electron injecting material include a metalcomplex compound and a nitrogen-containing five-membered ringderivative.

Examples of the metal complex compound include, but not limited to,8-hydroxyquinolinatolithium, tris(8-hydroxyquinolinato)aluminum, andbis(2-methyl-8-quinolinato)(1-naphtholato)aluminum.

The nitrogen-containing five-membered ring derivative is preferably aderivative of oxazole, thiazole, oxacliazole, thiadiazole, or triazole.

In the present invention, a benzimidazole derivative represented by anyof formulae (1) to (3) is preferred as the nitrogen-containingfive-membered ring derivative.

In formulae (1) to (3), Z¹, Z² and Z³ independently represent a nitrogenatom or a carbon atom.

R¹¹ and R¹² independently represent a substituted or unsubstituted arylgroup having 6 to 60 ring carbon atoms, a substituted or unsubstitutedheteroaryl group having 3 to 60 ring carbon atoms, an alkyl group having1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, oran alkoxy group having 1 to 20 carbon atoms.

Subscript m is an integer of 0 to 5. When m is an integer of 2 or more,the groups R¹¹ may be the same or different. Two adjacent groups R¹¹ maybe bonded to each other to form a substituted or unsubstituted aromatichydrocarbon ring. Examples of the substituted or unsubstituted aromatichydrocarbon ring include a benzene ring, a naphthalene ring, and ananthracene ring.

Ar¹ represents a substituted or unsubstituted aryl group having 6 to 60ring carbon atoms or a substituted or unsubstituted heteroaryl grouphaving 3 to 60 ring carbon atoms.

Ar² represents a hydrogen atom, an alkyl group having 1 to 20 carbonatoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy grouphaving 1 to 20 carbon atoms, a substituted or unsubstituted aryl grouphaving 6 to 60 ring carbon atoms, or a substituted or unsubstitutedheteroaryl group having 3 to 60 ring carbon atoms.

Ar³ represents a substituted or unsubstituted arylene group having 6 to60 ring carbon atoms or a substituted or unsubstituted heteroarylenegroup having 3 to 60 ring carbon atoms.

L¹, L² and L³ independently represent a single bond, a substituted orunsubstituted arylene group having 6 to 60 ring carbon atoms, asubstituted or unsubstituted fused heterocyclic group having 9 to 60ring atoms or a substituted or unsubstituted fluorenylene group.

In the organic EL device of the invention, the layer including thearomatic amine derivative of the invention may further include anemission material, a doping material, a hole injecting material or anelectron injecting material.

The layer including the aromatic amine derivative of the invention mayfurther include, if necessary, a material which is known as an emissionmaterial, a doping material, a hole injecting material, or an electroninjecting material, and the aromatic amine derivative may be used as adoping material.

By forming two or more organic thin film layers in an organic EL device,the decrease in the luminance and the lifetime due to the quenching canbe prevented. If necessary, an emission material, a doping material, ahole injecting material, and an electron injecting material may be usedin combination. The emission luminance and the emission efficiency canbe improved and the emission color can be changed by the use of a dopingmaterial.

The hole transporting layer of the organic EL device of the inventionmay be made into two-layered structure, i.e., a first hole transportinglayer (anode side) and a second hole transporting layer (cathode side).The aromatic amine derivative of the invention may be used in any of thefirst hole transporting layer and the second hole transporting layer.

In view of improving the stability to temperature, humidity, andatmosphere, the surface of the organic EL device of the presentinvention may be provided with a protective layer or the entire devicemay be protected by silicone oil or a resin.

Each layer of the organic EL device of the invention may be formed byany of a dry film-forming method, such as vacuum deposition, sputtering,plasma, and ion plating, and a wet film-forming method, such as spincoating, clipping, and flow coating.

In a dry film-forming method, the material for each layer is dissolvedor dispersed in an appropriate solvent, such as ethanol, chloroform,tetrahydrofuran, and dioxane, and the obtained solution or dispersion isformed into a thin film. The solution and dispersion may contain a resinor an additive to improve the film-forming property and prevent a pinhole in the layer. Examples of the resin include insulating resins, suchas polystyrene, polycarbonate, polyarylate, polyester, polyamide,polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate,cellulose, and copolymers thereof; photoconductive resins, such aspoly-N-vinylcarbazole and polysilane; and conductive resins such aspolythiophene and polypyrrole. Examples of the additive include anantioxidant, an ultraviolet absorber, and a plasticizer.

The thickness of each layer is not particularly limited and selected soas to obtain a good device performance. An excessively large thicknessincreases the applied voltage sufficient for obtaining a certain levelof optical output, resulting in a poor efficiency. An excessively smallthickness causes a pin hole, so a sufficient emission luminance cannotbe obtained even when an electric field is applied. The thickness ispreferably 5 nm to 10 μm and more preferably 10 nm to 0.2 μm.

EXAMPLES

The present invention will be described below in more detail withreference to the examples. However, it should be noted that the scope ofthe invention is not limited thereto.

Intermediate Synthesis 1-1 (Synthesis of Intermediate 1-1)

Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of4-iodobromobenzene, 22.3 g (105.0 mmol) of dibenzofuran-4-boronic acid,and 2.31 g (2.00 mmol) of Pd[PPh₃]₄, 150 ml of toluene, 150 ml ofdimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution ofNa₂CO₃ were added, and the resultant mixture was stirred for 10 h whilerefluxing under heating.

After the reaction, the obtained mixture was cooled to room temperatureand extracted with dichloromethane in a separatory funnel. The organiclayer was dried over MgSO₄, and then filtered and condensed. Thecondensate was purified by silica gel column chromatography to obtain26.2 g of a white solid, which was identified as the intermediate 1-1 byFD-MS analysis (Field Desorption Mass Spectrometry Analysis) (yield:81%).

Intermediate Synthesis 1-2 (Synthesis of Intermediate 1-2)

Under an argon atmosphere, into a mixture of 24.0 g (112.0 mmol) of4′-bromoacetanilide, 28.6 g (135.0 mmol) of dibenzofuran-4-boronic acid,and 2.6 g (2.24 mmol) of Pd[PPh₃]₄, 450 ml of toluene, 100 ml ofdimethoxyethane, and 110 ml (220.0 mmol) of a 2 M aqueous solution ofNa₂CO₃ were added, and the resultant mixture was stirred for 10 h whilerefluxing under heating.

After the reaction, the obtained mixture was cooled to room temperature,and the precipitated crystal was collected by filtration. The collectedcrystal was dissolved in tetrahydrofuran and filtered throughcelite/silica gel. The filtrate was condensed under reduced pressure.The obtained residue was washed with methanol/hexane and dried to obtain18.0 g of a white solid, which was identified as the intermediate 1-2 byFD-MS analysis (yield: 53%)

Intermediate Synthesis 1-3 (Synthesis of Intermediate 1-3)

Into 18.0 g (59.7 mmol) of the intermediate 1-2, 120 ml of xylene, 1200ml of water, and 60 ml of ethanol were added, and the resultant mixturewas stirred. After adding 20.0 g (360.0 mmol) of potassium hydroxide,the mixture was stirred for 10 h while refluxing under heating.

After the reaction, the obtained mixture was cooled to room temperatureand extracted with toluene in a separatory funnel. The organic layer wasdried over MgSO₄, and then filtered and condensed. The obtained residuewas recrystallized from xylene. The crystal was collected by filtrationand dried to obtain 14.7 g of a white solid, which was identified as theintermediate 1-3 by FD-MS analysis (yield: 95%).

Intermediate Synthesis 1-4 (Synthesis of Intermediate 1-4)

Under a nitrogen atmosphere, 150 g (0.89 mol) of dibenzofuran wasdissolved in 1000 ml of acetic acid under heating. After further adding188 g (1.18 mol) of bromine dropwise, the resultant mixture was stirredat room temperature for 20 h.

The precipitated crystal was collected by filtration and washedsuccessively with acetic acid and water. The recrystallization of thecrude product from methanol was repeated several times to obtain 66.8 gof a white crystal, which was identified as the intermediate 1-4 byFD-MS analysis (yield: 30%).

Intermediate Synthesis 1-5 (Synthesis of Intermediate 1-5)

Under an argon atmosphere, into 24.7 g (100.0 mmol) of the intermediate1-4, 400 ml of dry tetrahydrofuran was added and the resultant mixturewas cooled to −40° C. Further, 63 ml (100.0 mmol) of a 1.6 M hexanesolution of n-butyllithium was gradually added. The reaction solutionwas stirred for one hour while heating to 0° C. Then, the reactionsolution was cooled again to −78° C. and then a solution of 26.0 g(250.0 mmol) of trimethyl borate in 50 ml of dry tetrahydrofuran wasadded dropwise. After the dropwise addition, the reaction solution wasstirred at room temperature for 5 h. After adding 200 ml of a 1 Nhydrochloric acid, the solution was stirred for one hour and then theaqueous layer was removed. The organic layer was dried over MgSO₄, andthe solvent was evaporated off under reduced pressure. The obtainedsolid was washed with toluene to obtain 15.2 g of a white crystal(yield: 72%).

Intermediate Synthesis 1-6 (Synthesis of Intermediate 1-6)

Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of4-iodobromobenzene, 22.3 g (105.0 mmol) of the intermediate 1-5, and2.31 g (2.00 mmol) of Pd[PPh₃]₄, 150 ml of toluene, 150 ml ofdimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution ofNa₂CO₃ were added, and the resultant mixture was stirred for 10 h whilerefluxing under heating.

After the reaction, the obtained mixture was extracted withdichloromethane in a separatory funnel. The organic layer was dried overMgSO₄, and then filtered and condensed. The condensate was purified bysilica gel column chromatography to obtain 24.2 g of a white solid,which was identified as the intermediate 1-6 by FD-MS analysis (yield:75%).

Intermediate Synthesis 1-7 (Synthesis of Intermediate 1-7)

In the same manner as in Intermediate Synthesis 1-2 except for using28.6 g of the intermediate 1-5 in place of dibenzofuran-4-boronic acid,19.1 g of a white solid was obtained, which was identified as theintermediate 1-7 by FD-MS analysis (yield: 56%).

Intermediate Synthesis 1-8 (Synthesis of Intermediate 1-8)

In the same manner as in Intermediate Synthesis 1-3 except for using18.0 g of the intermediate 1-7 in place of the intermediate 1-2, 14.5 gof a white solid was obtained, which was identified as the intermediate1-8 by FD-MS analysis (yield: 93%).

Intermediate Synthesis 1-9 (Synthesis of Intermediate 1-9)

Under an argon atmosphere, into a mixture of 28.3 g (100.0 mmol) of4-iodobromobenzene, 23.9 g (105.0 mmol) of dibenzothiophene-4-boronicacid, and 2.31 g (2.00 mmol) of Pd[PPh₃]₄, 150 ml of toluene, 150 ml ofdimethoxyethane, and 150 ml (300.0 mmol) of a 2 M aqueous solution ofNa₂CO₃ were added, and the resultant mixture was stirred for 10 h whilerefluxing under heating.

After the reaction, the obtained mixture was cooled to room temperature,and extracted with dichloromethane in a separatory funnel. The organiclayer was dried over MgSO₄, and then filtered and condensed. Thecondensate was purified by silica gel column chromatography to obtain27.1 g of a white solid, which was identified as the intermediate 1-9 byFD-MS analysis (Field Desorption Mass Spectrometry Analysis) (yield:80%).

Intermediate Synthesis 1-10 (Synthesis of Intermediate 1-10)

Under an argon atmosphere, into a mixture of 24.0 g (112.0 mmol) of4′-bromoacetanilide, 30.8 g (135.0 mmol) of dibenzothiophene-4-boronicacid, and 2.6 g (2.24 mmol) of Pd[PPh₃]₄, 450 ml of toluene, 100 ml ofdimethoxyethane, and 110 ml (220.0 mmol) of a 2 M aqueous solution ofNa₂CO₃ were added, and the resultant mixture was stirred for 10 h whilerefluxing under heating.

After the reaction, the obtained mixture was cooled to room temperature,and the precipitated crystal was collected by filtration. The collectedcrystal was dissolved in tetrahydrofuran and filtered throughcelite/silica gel. The filtrate was condensed under reduced pressure.The obtained residue was washed with methanol/hexane and dried to obtain17.8 g of a white solid, which was identified as the intermediate 1-10by FD-MS analysis (yield: 50%)

Intermediate Synthesis 1-11 (Synthesis of Intermediate 1-11)

Into 18.0 g (56.1 mmol) of the intermediate 1-10, 120 ml of xylene, 1200ml of water, and 60 ml of ethanol were added, and the resultant mixturewas stirred. After adding 20.0 g (360.0 mmol) of potassium hydroxide,the mixture was stirred for 10 h while refluxing under heating.

After the reaction, the obtained mixture was cooled to room temperatureand extracted with toluene in a separatory funnel. The organic layer wasdried over MgSO₄ and then filtered and condensed. The obtained residuewas recrystallized from xylene. The crystal was collected by filtrationand dried to obtain 14.7 g of a white solid, which was identified as theintermediate 1-11 by FD-MS analysis (yield: 95%).

Intermediate Synthesis 1-12 (Synthesis of Intermediate 1-12)

In the same manner as in Intermediate Synthesis 1-5 except for using26.3 g of 2-bromodibenzothiophene in place of the intermediate 1-4, 15.0g of a white solid was obtained (yield: 66%).

Intermediate Synthesis 1-13 (Synthesis of Intermediate 1-13)

In the same manner as in Intermediate Synthesis 1-6 except for using23.9 g of the intermediate 1-12 in place of the intermediate 1-5, 25.4 gof a white solid was obtained, which was identified as the intermediate1-13 by FD-MS analysis (yield: 75%).

Intermediate Synthesis 1-14 (Synthesis of Intermediate 1-14)

In the same manner as in Intermediate Synthesis 1-2 except for using30.8 g of the intermediate 1-12 in place of dibenzofuran-4-boronic acid,18.1 g of a white solid was obtained, which was identified as theintermediate 1-14 by FD-MS analysis (yield: 51%).

Intermediate Synthesis 1-15 (Synthesis of Intermediate 1-15)

In the same manner as in Intermediate Synthesis 1-3 except for using18.0 g of the intermediate 1-14 in place of the intermediate 1-2, 13.9 gof a white solid was obtained, which was identified as the intermediate1-15 by FD-MS analysis (yield: 90%).

Intermediate Synthesis 2-1 (Synthesis of Intermediate 2-1)

Under an argon atmosphere, into a mixture of 19.9 g (50.0 mmol) of2-bromo-9,9′-diphenylfluorene, 13.0 g (50.0 mmol) of the intermediate1-3, and 9.6 g (100.0 mmol) of t-butoxysodium, 250 ml of dry toluene wasadded, and the resultant mixture was stirred. After adding 225 mg (1.0mmol) of palladium acetate and 202 mg (1.0 mmol) oftri-t-butylphosphine, the mixture was allowed to react at 80° C. for 8h.

After cooling, the reaction mixture was filtered through celite/silicagel. The filtrate was condensed under reduced pressure. The obtainedresidue was recrystallized from toluene and the crystal was collected byfiltration and dried to obtain 23.0 g of a white solid, which wasidentified as the intermediate 2-1 by FD-MS analysis (yield: 80%).

Intermediate Synthesis 2-2 (Synthesis of Intermediate 2-2)

In the same manner as in Intermediate Synthesis 2-1 except for using13.0 g of the intermediate 1-8 in place of the intermediate 1-3, 23.2 gof a white solid was obtained, which was identified as the intermediate2-2 by FD-MS analysis (yield: 81%).

Intermediate Synthesis 2-3 (Synthesis of Intermediate 2-3)

In the same manner as in Intermediate Synthesis 2-1 except for using10.5 g of 2-amino-9,9′-dimethylfluorene in place of the intermediate1-3, 19.7 g of a white solid was obtained, which was identified as theintermediate 2-3 by FD-MS analysis (yield: 75%).

Intermediate Synthesis 2-4 (Synthesis of Intermediate 2-4)

In the same manner as in Intermediate Synthesis 2-1 except for using13.8 g of the intermediate 1-11 in place of the intermediate 1-3, 23.7 gof a white solid was obtained, which was identified as the intermediate2-4 by FD-MS analysis (yield: 80%).

Intermediate Synthesis 2-5 (Synthesis of Intermediate 2-5)

In the same manner as in Intermediate Synthesis 2-1 except for using13.8 g of the intermediate 1-15 in place of the intermediate 1-3, 22.2 gof a white solid was obtained, which was identified as the intermediate2-5 by FD-MS analysis (yield: 75%).

Synthesis Example 1 (Production of Aromatic Amine Derivative H1)

Under an argon atmosphere, into a mixture of 3.2 g (10.0 mmol) of theintermediate 1-1, 5.8 g (10.0 mmol) of the intermediate 2-1, 0.14 g(0.15 mmol) of Pd₂(dba)₃, 0.087 g (0.3 mmol) of P(tBu)₃HBF₄, and 1.9 g(20.0 mmol) of t-butoxysodium, 50 ml of dry xylene was added, and theresultant mixture was refluxed for 8 h under heating.

After the reaction, the reaction liquid was cooled to 50° C. andfiltered through celite/silica gel. The filtrate was condensed and theobtained condensate was purified by silica gel column chromatography toobtain a white solid. The crude product was recrystallized from tolueneto obtain 3.7 g of a white crystal, which was identified as the aromaticamine derivative H1 by FD-MS analysis (yield: 45%).

Synthesis Example 2 (Production of Aromatic Amine Derivative H2)

In the same manner as in Synthesis Example 1 except for using 3.2 g ofthe intermediate 1-6 in place of the intermediate 1-1 and using 5.8 g ofthe intermediate 2-2 in place of the intermediate 2-1, 5.2 g of a whitecrystal was obtained, which was identified as the aromatic aminederivative H2 by FD-MS analysis (yield: 63%).

Synthesis Example 3 (Production of Aromatic Amine Derivative H3)

In the same manner as in Synthesis Example 1 except for using 3.2 g ofthe intermediate 1-6 in place of the intermediate 1-1, 4.5 g of a whitecrystal was obtained, which was identified as the aromatic aminederivative H3 by FD-MS analysis (yield: 55%).

Synthesis Example 4 (Production of Aromatic Amine Derivative H4)

In the same manner as in Synthesis Example 1 except for using 2.3 g of4-bromobiphenyl in place of the intermediate 1-1, 3.6 g of a whitecrystal was obtained, which was identified as the aromatic aminederivative H4 by FD-MS analysis (yield: 50%).

Synthesis Example 5 (Production of Aromatic Amine Derivative H5)

Under an argon atmosphere, into a mixture of 2.3 g (10.0 mmol) of2-bromobiphenyl, 5.3 g (10.0 mmol) of the intermediate 2-3, 0.14 g (0.15mmol) of Pd₂(dba)₃, 0.087 g (0.3 mmol) of P(tBu)₃HBF₄, and 1.9 g (20.0mmol) of t-butoxysodium, 50 ml of dry xylene was added, and theresultant mixture was refluxed for 8 h under heating.

After the reaction, the reaction liquid was cooled to 50° C. andfiltered through celite/silica gel. The filtrate was condensed and theobtained condensate was purified by silica gel column chromatography toobtain a white solid. The crude product was recrystallized from tolueneto obtain 3.1 g of a white crystal, which was identified as the aromaticamine derivative H5 by FD-MS analysis (yield: 45%).

Synthesis Example 6 (Production of Aromatic Amine Derivative H6)

In the same manner as in Synthesis Example 5 except for using 2.3 g of4-bromobiphenyl in place of 2-bromobiphenyl, 2.7 g of a white crystalwas obtained, which was identified as the aromatic amine derivative H6by FD-MS analysis (yield: 40%).

Synthesis Example 7 (Production of Aromatic Amine Derivative H7)

In the same manner as in Synthesis Example 1 except for using 3.4 g ofthe intermediate 1-9 in place of the intermediate 1-1 and using 5.9 g ofthe intermediate 2-4 in place of the intermediate 2-1, 4.7 g of a whitecrystal was obtained, which was identified as the aromatic aminederivative H7 by FD-MS analysis (yield: 55%).

Synthesis Example 8 (Production of Aromatic Amine Derivative H8)

In the same manner as in Synthesis Example 1 except for using 3.4 g ofthe intermediate 1-13 in place of the intermediate 1-1 and using 5.9 gof the intermediate 2-5 in place of the intermediate 2-1, 5.1 g of awhite crystal was obtained, which was identified as the aromatic aminederivative H8 by FD-MS analysis (yield: 55%).

Example 1-1 Production of Organic EL Device

A glass substrate with an ITO transparent electrode line having a sizeof 25 mm×75 mm×1.1 mm (manufactured by GEOMATEC Co., Ltd.) wasultrasonically cleaned in isopropyl alcohol for 5 min and then UV(ultraviolet)/ozone cleaned for 30 min.

The cleaned glass substrate with the transparent electrode line wasmounted on the substrate holder of a vacuum deposition apparatus. First,the following electron-accepting compound A was vapor-deposited onto thesurface on the side where the transparent electrode line was formed soas to cover the transparent electrode, thereby forming a film A having athickness of 5 nm.

On the film A, the following aromatic amine derivative X1 as a firsthole transporting material was vapor-deposited to form a first holetransporting layer having a thickness of 160 nm. Successively after theformation of the first hole transporting layer, the aromatic aminederivative H1 as a second hole transporting material was vapor-depositedto form a second hole transporting layer having a thickness of 10 nm.

On the hole transporting layer, the host compound BH and the dopantcompound BD were vapor co-deposited into a film having a thickness of 25nm, to form a light emitting layer. The concentration of the dopantcompound BD was 4% by mass.

On the light emitting layer, the compound ET1 was vapor-deposited in athickness of 20 nm and then the compound ET2 and Li were vaporco-deposited each in a thickness of 10 nm and 25 nm, thereby forming anelectron transporting/injecting layer. The concentration of Li was 4% bymass.

Then, metallic Al was deposited in a thickness of 80 nm to form acathode, thereby producing an organic EL device.

Examples 1-2 to 1-6

Each organic EL device of Examples 1-2 to 1-6 was produced in the samemanner as in Example 1-1 except for using each aromatic amine derivativelisted in Table 1 as the second hole transporting material.

Comparative Examples 1-1 and 1-2

Each organic EL device of Comparative Examples 1-1 and 1-2 was producedin the same manner as in Example 1-1 except for using each aromaticamine derivative listed in Table 1 as the second hole transportingmaterial.

Evaluation of Emission Performance of Organic EL Device

Each organic EL device thus produced was measured for the luminance (L)and the current density by allowing the device to emit light under adirect current drive. Using the measured results, the current efficiency(L/J) and the driving voltage (V) at a current density of 10 mA/cm² weredetermined. In addition, the organic EL device was measured for thelifetime at a current density of 50 mA/cm². The 80% lifetime is the timetaken until the luminance was reduced to 80% of the initial luminancewhen driving the device at constant current. The results are shown inTable 1.

TABLE 1 Measured Results First hole Second hole Emission Driving 80%transporting transporting efficiency (cd/A) voltage (V) Lifetimematerial material @10 mA/cm² @10 mA/cm² (h) Examples 1-1 X1 H1 6.5 4.2230 1-2 X1 H2 6.9 4.2 190 1-3 X1 H3 7.2 4.2 220 1-4 X1 H4 6.2 4.0 1701-5 X1 H7 6.4 4.1 210 1-6 X1 H8 7.0 4.1 180 Comparative Examples 1-1 X1comparative 5.5 4.2 120 compound 1 1-2 X1 comparative 5.2 4.0 100compound 2

The results of Table 1 show that an organic EL device having a highefficiency even when driving it at a low voltage and having a longlifetime is obtained by using the aromatic amine derivative of theinvention.

Example 2-1 Production of Organic EL Device

A glass substrate with an ITO transparent electrode line having a sizeof 25 mm×75 mm×1.1 mm (manufactured by GEOMATEC Co., Ltd.) wasultrasonically cleaned in isopropyl alcohol for 5 min and then UV(ultraviolet)/ozone cleaned for 30 min.

The cleaned glass substrate with the transparent electrode line wasmounted on the substrate holder of a vacuum deposition apparatus. First,the following electron-accepting compound A was vapor-deposited onto thesurface on the side where the transparent electrode line was formed soas to cover the transparent electrode, thereby forming a film A having athickness of 5 nm.

On the film A, the following aromatic amine derivative H5 as a firsthole transporting material was vapor-deposited to form a first holetransporting layer having a thickness of 160 nm. Successively after theformation of the first hole transporting layer, the aromatic aminederivative Y1 as a second hole transporting material was vapor-depositedto form a second hole transporting layer having a thickness of 10 nm.

On the hole transporting layer, the host compound BH and the dopantcompound BD were vapor co-deposited into a film having a thickness of 25nm, to form a light emitting layer. The concentration of the dopantcompound BD was 4% by mass.

On the light emitting layer, the compound ET1 was vapor-deposited in athickness of 20 nm and then the compound ET2 and Li were vaporco-deposited each in a thickness of 10 nm and 25 nm, thereby forming anelectron transporting/injecting layer. The concentration of Li was 4% bymass.

Then, metallic Al was deposited in a thickness of 80 nm to form acathode, thereby producing an organic EL device.

Examples 2-2 to 2-4

Each organic EL device of Examples 2-2 to 2-4 was produced in the samemanner as in Example 2-1 except for using the aromatic amine derivativeslisted in Table 2 as the first hole transporting material and the secondhole transporting material.

Comparative Examples 2-1 and 2-2

Each organic EL device of Comparative Examples 2-1 and 2-2 was producedin the same manner as in Examples 2-1 and 2-2, respectively, except forusing NPD as the first hole transporting material.

Evaluation of Emission Performance of Organic EL Device

Each organic EL device thus produced was measured for the luminance (L)and the current density by allowing the device to emit light under adirect current drive. Using the measured results, the current efficiency(L/J) and the driving voltage (V) at a current density of 10 mA/cm² weredetermined. In addition, the organic EL device was measured for thelifetime at a current density of 50 mA/cm². The 80% lifetime is the timetaken until the luminance was reduced to 80% of the initial luminancewhen driving the device at constant current. The results are shown inTable 2.

TABLE 2 Measured Results First hole Second hole Emission Driving 80%transporting transporting efficiency (cd/A) voltage (V) Lifetimematerial material @10 mA/cm² @10 mA/cm² (h) Examples 2-1 H5 Y1 8.3 4.0150 2-2 H5 Y2 8.5 4.0 230 2-3 H6 Y1 8.1 4.0 130 2-4 H6 Y2 8.4 4.0 180Comparative Examples 2-1 NPD Y1 7.2 4.2 110 2-2 NPD Y2 6.2 4.2 130

The results of Table 2 show that an organic EL device having a highefficiency even when driving it at a low voltage and having a longlifetime is obtained by using the aromatic amine derivative of theinvention.

1. (canceled)
 2. An aromatic amine derivative represented by formula(1):

wherein in formula (1): R¹, R² and R³ each independently represents ahydrogen atom or an alkyl group having 1 to 20 carbon atoms; krepresents an integer of 1 to 5; m represents an integer of 1 to 4; nrepresents an integer of 1 to 3; when groups R¹ exist, the groups R¹ maybe the same or different, when groups R² exist, the groups R² may be thesame or different, and when groups R³ exist, the groups R³ may be thesame or different; L represents a single bond or a divalent grouprepresented by formula (16):

wherein in formula (16): R¹ represents a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, or an aryl group having 6 to 12 ring carbonatom; m represents an integer of 1 to 4; and when groups R¹ exist, thegroups R¹ may be the same or different; Ar¹ represents a grouprepresented by formula (30):

wherein in formula (30): R¹ represents a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, or an aryl group having 6 to 12 ring carbonatom; m represents an integer of 1 to 4; when groups R¹ exist, thegroups R¹ may be the same or different; and one of two R⁴ represents amethyl group or a phenyl group and the other represents a methyl group;Ar² represents a group represented by formula (7-2):

wherein in formula (7-2): R¹ represents a hydrogen atom, an alkyl grouphaving 1 to 5 carbon atoms, or an aryl group having 6 to 12 ring carbonatoms; k represents an integer of 1 to 5; m represents an integer of 1to 4; and when groups R¹ exist, the groups R¹ may be the same ordifferent.
 3. The aromatic amine derivative according to claim 2,wherein R¹, R² and R³ in formula (1) each independently represents ahydrogen atom, a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, an isobutyl group, a s-butyl group, ora t-butyl group.
 4. The aromatic amine derivative according to claim 2,wherein R¹ in formula (30) represents a hydrogen atom, a phenyl group ora biphenylyl group.
 5. The aromatic amine derivative according to claim2, wherein R¹ in formula (7-2) represents a hydrogen atom, a phenylgroup or a naphthyl group.
 6. The aromatic amine derivative according toclaim 2, wherein R′, R² and R³ in formula (1) represent hydrogen atoms.7. The aromatic amine derivative according to claim 2, wherein R¹ informula (16) represents a hydrogen atom.
 8. The aromatic aminederivative according to claim 2, wherein R¹ in formula (30) represents ahydrogen atom.
 9. The aromatic amine derivative according to claim 2,wherein R¹ in formula (7-2) represents a hydrogen atom.
 10. The aromaticamine derivative according to claim 2, wherein R¹, R² and R³ in formula(1), R¹ in formula (16), R¹ in formula (30), and R¹ in formula (7-2)represent hydrogen atoms.
 11. The aromatic amine derivative according toclaim 2, wherein the aromatic amine derivative is any one of thefollowing compounds:


12. An organic electroluminescence device comprising an anode, acathode, and at least one organic thin film layer disposed between theanode and the cathode, wherein: the at least one organic thin film layercomprises a light emitting layer; and at least one organic thin filmlayer comprises the aromatic amine derivative according to claim
 2. 13.The organic electroluminescence device according to claim 12, wherein:the at least one organic thin film layer comprises a hole injectinglayer or a hole transporting layer; and the hole injecting layer or thehole transporting layer comprises the aromatic amine derivative.
 14. Theorganic electroluminescence device according to claim 12, wherein: theat least one organic thin film layer comprises a hole transportinglayer; the hole transporting layer comprises a first hole transportinglayer at an anode side and a second hole transporting layer at a cathodeside; and any of the first hole transporting layer and the second holetransporting layer comprises the aromatic amine derivative.
 15. Theorganic electroluminescence device according to claim 14, wherein thefirst hole transporting layer comprises the aromatic amine derivative.